Safety valve assembly for controlling clutch and brake in power press or the like

ABSTRACT

A valve assembly for a pressurized fluid line controlling a clutch and brake made up of a pair of valves having movable valve members with separate actuators, each of the valve members having inlet ports and outlet ports, the inlet ports being connected in series and the outlet ports being connected effectively in parallel so that both valves must be activated to pass the pressurized fluid to the control line and so that upon unwanted sticking of one of the valve members in activated position, pressure fluid to the control line is cut off and exhaust fluid from the line is promptly and directly vented.

United States Patent Mahorney, deceased et al.

[5 SAFETY VALVE ASSEMBLY FOR [56] References Cited CONTROLLING CLUTCHAND BRAKE IN UNITED STATES PATENTS POWER PRESS OR THE LIKE 3.043.3357/1962 l37/596.|5 [751 Inventors. Kenneth Mahomey deceasc 3.265.0898/l966 Nill l37/596.l6 by Ardith Mahorney lei-la 3.603.348 9/l97l Wrlghtl37/596.l6 representative, Bartlett. lll. M P Sch d Prima Examinerartinwa ron [73] Asslgnee: Ross q i valve company Assistgt E.mminer--RobertJ. Miller Demm Mich Attorney, Agent, or Firm-Harness, Dickey & Pierce[22] Filed: Sept. 14, 1973 21 Appl. No.: 397,300 [5 AB R T Related U s.Pawn Documents A valve assembly for a pressurized fluid line control R Iling a clutch and brake made up of a pair of valves elssue 0 havingmovable valve members with separate actua- [64] Pawn 3'670767 tors, eachof the valve members having inlet ports and Issued: June I972 outletports, the inlet ports being connected in series and the outlet portsbeing connected effectively in Ffled: 1971 parallel so that both valvesmust be activated to pass the pressurized fluid to the control line andso that [52] US. Cl. 137/596 upon unwanted sticking of one of the valvemembers [5i] Int. Fl6k 11/10 in activated position. pressure fluid tothe Control line [58] Field 0 Search 137/596, 596.12, 596. i4, is cut fand exhaust fluid from the line is promptly l37/596.l6, 596.17, 596.18,625.66 625.6, and directly vemfi 14 Claims, 5 Drawing Figures 26 6?. 3 r507' Add OPE/V 2 H i 1"2 4 f 1:", vy/ya" f "7' 4 r. a

II 4 p v I x, l3 rw/a 25 21 41 SUPPLY f.-

' -1 I is jfi 53 r 38 l L I I 32 5; l 4 w cmvma; 4 1 137 i l *1 LINE I vli 38 V I Q? K ,JL. 44 r fEXHAU 5 Z2 1; i 2 4 24 0 454:. 0 27 .4 2 I "iN 4| 0 x ID I kk g 1 ,IE mar 1g 4 near I a e4; WM" 13' I 40 4/ k 43 l/ a432 Reissued Aug. 19, 1975 Re. 28,520

2 Sheets-Sheet 1 FIG. L 2G) 26 L142 Reissued Aug. 19, 1975 Re. 28,520

2 Sheets-Sheet 2 61 26 C 62 F'G-B 25 5w A S TUCK OPE/V SAFETY VALVEASSEMBLY FOR CONTROLLING CLUTCH AND BRAKE IN POWER PRESS OR THE LIKEMatter enclosed in heavy brackets appears in the original patent butforms no part of this reissue specification; matter printed in italicsindicates the additions made by reissue.

It has been recognized in the past that use of a simple three-way valvefor alternatively admitting pressurized fluid to a clutch and brakecontrol line in a power press, and exhausting fluid therefrom, does notprovide adequate safety since sticking of the valve in its activated"condition may prevent the slide from safely coming to rest at the top ofthe stroke at the completion of a press cycle. Unwanted descent of theslide may cause a serious accident. To provide a safety factor it hasbeen proposed in the past that two separately actuated three-way valvesbe connected in parallel with one another. Thus if one of the valvessticks in its open or activated position the fluid which is passed isharmlessly vented through the companion valve. The drawback to this isthat the flow of vented fluid is so great as to produce a condition ofpartial or back pressure in the control line so that the clutch may becompletely disengaged nor the brake surfaces fully seated.

It has also been proposed to connect two three-way valves effectively inseries with one another which insures shut-off of the pressurized fluidin the event that one of the valves sticks in open position. The problemhere is that where the downstream valve is the sticking one the fluidwhich is exhausted from the control line must be exhausted through inletports, which are usually quite restricted in cross section, which delaysventing and therefore delays de-clutching and setting of the brake.

It is, accordingly, an object of the present invention to provide avalve assembly in which both ofthese undesirable conditions areobviated. More specifically it is an object of the invention to providea valve assembly having first and second separately actuated valvemembers which have inlet ports connected in series so that pressurizedfluid cannot flow as long as at least one of the valve members respondsto the deactuation and which insures prompt and direct venting of thecontrol line to near zero pressure without necessity for the exhaustedfluid to traverse the inlet ports of either of the two valves.

Other objects and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings in which:

FIG. I shows. in cross section, a valve assembly con structed inaccordance with the present invention and employing two separatelyactuated valve members which are both in activated" condition forpressurizing the clutch and brake control line.

FIG. 2 shows the valve assembly of FIG. I in deactuated condition withboth of the valve members turned off and with the control line beingvented to the exhaust condition.

FIG. 3 shows the condition of the valve assembly with the second valvemember inadvertently stuck in open condition.

(ill

FIG. 4 shows the assembly with the first valve member stuck in opencondition.

While the invention is described in connection with a preferredembodiment, it will be understood that I do not intend to limit theinvention to the particular em bodiment shown but intend, on thecontrary, to cover the various alternative and equivalent valveconstructions which are included within the spirit and scope of theappended claims.

Turning now to FIG. 1, a frame or housing 10 is provided mounting a pairof valve members 1], 12. Ports are provided in the valve housing forconnection to an air supply line 13, a control, or output, line 14, andan exhaust line 15. The valve members are, in the present instance, inthe form of spools mounted for vertical movement. Taking the spool 11 byway of example, in portion A of the valve. it has spaced, inwardlyfacing flanges 21, 22 cooperating with respectively opposed valve seats23, 24. The valve seats are spaced axially by a lesser distance than theflanges so that the valve spool is movable between limit positions, thatis, between an upper position, which will also be referred to as an"activated or on position in which the upper seat 23 is open, and alower position. also referred to as a deactivated" or off position, inwhich the upper seat 23 is sealed off. For permitting endwise movementof the valve spool, the spool has a cylindrical projection 25 at itsupper end which is slidable in a bore 26 as well as a cylindricalprojection 27 at its lower end slidable in a bore 28. The central stemof the valve spool. which is of reduced diameter, and which is indicatedat 31, is snugly fitted and slideable within a central land 32.

For convenience the seats 23, 24 and central land 32 are all formed on acylindrical insert 35 which is scaled to the body or housing 10 of thevalve by suitable O- rings. The cylindrical insert 35 is provided withsets of lateral openings 36, 37, which sets may be respectively four innumber and arranged, as shown, at two different levels. The insert 35 issealed at three levels by ()-rings 38.

For the purpose of moving the valve spool ll to its upper or on positionas shown in FIG. 1. the lower end of the valve spool is engaged by aflexible diaphragm 40, defining below it a space 41 into which air orother pressurized fluid may be admitted through a pilot orifice 42.

The pilot orifice 42 is supplied with air or other piloting fluid from apilot valve 43 which may be connected to the same supply line 13 whichserves as the source of pressure fluid and with the valve being operatedby a solenoid 44 under the control of electrical line 45. The pilotvalve 43 and solenoid 44 will be understood to be conventional andreadily available, in combined form, as a commercial unit.

Turning attention next to the valve member. or spool, 12 in part B ofthe valve. and the cylindrical insert which cooperates with it. it willbe noted that the construction is the same and, accordingly.corresponding elements have been designated by corresponding refer encenumerals with the addition of subscript a. The spool is actuated by adiaphragm 40a under the control of a pilot valve and solennoid 43a, 44a.

In accordance with the present invention the valve housing l0 includes asupply line chamber Sl, an intermediate chamber 52, a control linechamber 53 and an exhaust line chamber 54. The seat 23 of the firstmovable valve member is interposed bctween the fluid supply line chamber51 and the intermediate chamber 52 whereas the seat 23a. associated withthe second valve member is interposed between the intermediate chamber52 and the control line chamber 53 so that the pres sure fluid enteringat the chamber 5] is conducted past the valve seat 23 then past thevalve seat 23a before passing into the control line. Stated in simpleterms. the inlet ports of the two valve members are connected in serieswith one another. Since, before pressurized fluid can be passed to thecontrol line 14, such fluid must flow in succession past the seats 23,23a, both of the valve members I], 12 must be in their activated or onpositions, and the failure of either valve element to be in suchposition prevents pressure from passing into the control line.

Further in accordance with the invention the valve seats 24, 24a areboth directly interposed between the control line chamber 53 and theexhaust line chamber 54 so that when the valve members are in theirupper position shown in FIG. 1 the exhaust line is sealed off, but whenvalve members are in their lower or of? position, pressurized fluid inthe control line 14 is free to escape, or be vented, past both of theseats 24, 24a into the exhaust line 15. It is the latter condition whichis illustrated in FIG. 2 which shows the diaphragms 40. 40a collapsedand with the valve members 8, l2 lowered by gravity to seal off theupper, or inlet seats 23, 23a while opening both of the exhaust seats24, 24a.

Since the pressurized fluid from the control line 14 is free to escapesimultaneously past both of the seats 24. 24a, such seats areeffectively connected in parallel with one another. The advantage ofthis is that in the event that either of the valve members ll, 12 shouldfail to respond, or drop, from the on" position shown in FIG. 1 to theofl position shown in FIG. 2, the pressurized fluid in the control linel4 will nevertheless be directly and fully vented to the exhaust line 15producing an immediate drop in the pressure of the control line to zero.Note that the term directly vented" has been employed which makes itclear that pressurized fluid from the control line is directly ventedpast a single valve seat into the exhaust line. This is to be contrastedwith prior series valve systems which did provide positive cut off ofpressurized fluid but which also required that the venting occur inseries relation past two successive valve seats presenting anobstruction to the flow of fluid and a delay in the venting cycle Theadditional safety provided by the present valve assembly will beapparent upon inspection of FIGS. 3 and 4 which show the movable valvemembers respectively stuck in the upper or *on" position.

Thus focusing attention upon FIG. 3 the second portion B of the valve,formed by the valve member 12, is shown stuck in open position Suchsticking may be either due to the physical sticking of the valve member[2 within the housing 10, to the sticking of the pilot valve 43a orsolenoid 44a which controls it, or to an electrical malfunction whichfails to turn off the solenoid 44a upon command In short, anymalfunction which causes the valve member 12 to remain in its upper oron" position when it should be turned off is covered by the general termsue-king." In any event, since the inlet valve seats 23, 2321 areconnected, as shown, in series with one another, the fact that the valvemember 11 has responded to the command to drop and is in its lowerposition insures that the flange 2] is seated against the seat 23thereby precluding any flow of pressurized fluid from the fluid supplyline [3 into the control line 14. Moreover, since the valve member 11has, on command, dropped to its lower position, flange 22 has separatedfrom seat 24 providing a large and direct connection between the controlline chamber 53 and the exhaust line chamber 54 for immediate andcomplete venting of pressure fluid from the control line 14 into theexhaust line 15. Thus the control line 14 is reliably and completelyvented to turn off the clutch of the power press or other controlledmachine, and to set the brake, notwithstanding the fact that one half ofthe valve assembly has failed to respond to command.

Equal protection is provided in the event that the valve member 11 failsto respond as shown in FIG. 4. In this figure the valve member 11 isstuck, either by reason of physical sticking within the housing or byreason of the fact that the pilot valve which controls it has failed torespond. This leaves the seat 23 uncovered so that pressure fluid mightenter, but the fact that the valve member 12 has dropped in accordancewith command has sealed the valve seat 23a, which is in series with theseat 23, so that pressure fluid is positively blocked against enteringthe control line 14. Also, while sticking of the valve member 11 in itsupper position has failed to uncover the exhaust seat 24, the fact thatthe valve member 12 has dropped, opens the valve seat 24a to permitimmediate and complete venting of pressure fluid from the control line14 through control line chamber 53 and into exhaust line chamber 54 tothe exhaust line 15. Accordingly the pressure in the control line 14drops to zero to turn off the clutch and set the brake.

The press, in view of the safety factor provided by the aboveseries-parallel assembly, could be operated indefinitely with one sideof the valve in stuck condition without the operator being aware.Therefore, detector switches 61, 62 are provided responsive to the axialmovements of the valve members and suitably connected to the presscontrol circuitry in such a way as to prevent the next succeeding oncommand if either valve fails to respond to the off command. It is,however, unnecessary to show the press control circuitry in order toillustrate the function of the switches and this function may beillustrated by assuming that the switches are connected to individuallamps 63, 64. Where such lamps are employed flashing of each lamp duringa single press cycle will serve to assure the operator that both sidesof the valve assembly are fully operative. whereas failure of one of thelamps to flash, either by remaining on, or by remaining off, denotesthat one side of the valve is stuck so that the press may be shut downuntil the situation is remedied. In short, while the series-parallelvalving arrangement prevents a dangerous malfunction of the press uponfailure of a portion of the valve, it is not intended that the presscontinue to be operated unless both portions of the valve assembly arein working order.

The invention has been discussed in connection with control of a powerpress wherein failure of the slide to come to rest at the top of thestroke may create hazard ous conditions for the operator and the pressitself. It will be apparent, however, that the present valve is notlimited to use with a power press, and it will be understood that thevalve assembly has general utility wherever it is necessary to control apotentially hazardous piece of mechanism by pressure or complete lack ofpressure in a control line,

While the construction has been discussed above relating the valve seatsto the chambers Sl54, it may be helpful, in understanding theconstruction, to consider that the first portion A of the valve is adouble two-way valve having a total of four ports communicating with therespective chambers Sl54 while the second portion B of the val e is athree-way valve connected at its ends to chambers 52, 54 but with all ofthe central ports being connected to the control line chamber 53.

I claim as my invention:

1. A safety valve assembly for supplying pressurized fluid from a supplyline to a clutch and brake control line to energize the clutch andde-energize the brake and for alternatively exhausting fluid from thecontrol line to an exhaust line to de-energize the clutch and energizethe brake which comprises means defining a fluid supply line chamber andan intermediate chamber as well as a control line chamber and an exhaustline chamber. a first valve having a movable valve member cooperatingwith first and second seats, the first seat being normally closed andthe second scat being normally open and having an actuator foractivating such valve member, a second valve having a movable valvemember cooperating with third and fourth seats, the third seat beingnormally closed and the fourth seat being normally open and having anactuator for activating such valve member. the flrst seat beinginterposed between the supply line chamber and the intermediate chamberand the third seat being interposed between the intermediate chamber andthe control line chamber so that such seats are effectively in serieswith one another with pressurized fluid being passed successivelythrough the first and third seats from the supply line chamber to thecontrol line chamber when the valve members are simultaneously activatedby the actuators, the second and fourth seats being both interposed between the control line chamber and the exhaust line chamber with suchseats being effectively in parallel with one another so that in theevent either one of the movable valve members, upon deactuation, sticksin its activated position a) flow of pressurized fluid from the supplyline will be cut off and (b) [direct access] a dircct path for exhaustedfluid will be provided from the control line to the exhaust line whichbypasses suidjirst and third suits for insuring that the clutch andbrake are in a safe condition.

2. The combination as claimed in claim 1 in which the movable valvemembers are each in the form of a spool having spaced, inwardly facingflanges cooperating with opposed outwardly facing valve seats with thespools being movable endwise through a limited displacement foralternative closing of the valve seats 3. The combination as claimed inclaim 2 in which the valve seats cooperating with a given spool areformed at the respective ends of a cylindrical insert having lateralopenings formed therein 4. The combination as claimed in claim 1 inwhich the housing means is unitary enclosing all of said chambers andseats and with means for guiding the movable valve members into seatedcondition with respect to the seats.

5. A safety valve assembly for supplying pressurized fluid from a supplyline to a clutch and brake control line to energize the clutch andde-energize the brake and for alternatively exhausing the fluid from thecontrol line to an exhaust line to tic-energize the clutch and energizethe brake, which comprises a first valve in the form of a double two-wayvalve having first and second valve seats defining a total of fourports, the seats being engaged by a valve member movable between limitpositions for closing the seats alternatively, a second valve in theform ofa threeway valve having third and fourth valve seats defining atotal of three ports, the seats being engaged by a valve member movablebetween limit positions for closing the seats alternatively, separateactuating means for activating the valve members, means forinterconnecting the ports associated with the first and third valveseats in series so that when the valve members are both activated,pressurized fluid is conducted in succession past the first and thirdvalve seats, means for interconnecting the ports associated with thesecond and fourth valve seats in parallel so that when the valve membersare both deactuatcd, exhausted fluid is conducted in parallel past thesecond and fourth valve seats and so that in the event one of the valvemembers, upon being deactuated, sticks in its activated position atleast the second or fourth seat will remain open to provide directescape of exhausted fluid from the control line.

6. The combination as claimed in claim 5 in which means are provided forsignalling the sticking of one of the valve members 7. A sufcty controlsvvtcm jorfhtid ttcluutcd dcviccs, comprising housing means having (1supply port, a control port and at least onc exhaust port, first andsecond vulvc means in said housing means, each vulvc means having supplyand cxhuust vulvc mwnbcrs movable simulttim'ously bctwccn (1 supplyposition in which the supply vulvc mcmber is open and thc exhaust valvemember closed, and (Ill (ht/UNIS! position in which [he (.tlltlllSlvulvc mtmbcr is opcn and the supply vulvc mcmhcr is closed, meansconnecting thc supply vulvc mcmbcrs of suit/firs! and second vulvc mcunsin series bctwccn said supply and control ports, and mcuns connectingthe c,\- hails! valve members ofsaidjirs! and sccond vulvc mcuns inparallel bctwccn said control and tit/MUS! ports, whereby lhc movcmcnlofcirhcr vulvc mcuns to its c1 Imus! position when the other valve meansremains par tially orfully in its supply position will result in a complctc cutoff offluid prcssurcfrom the supply to the control port and adircct connection from the control port to at least one of the exhaustports, said direct connection bypassing the supply valve members of both.s'uiiijirs! and second valve means;

8, The combination according to claim 7, cuch valve means comprising aspool with inwardly facing flanges comprising Ihc supply and exhaustvalve mcmbcrs:

9. The combination according to claim 8, said control port beingconnected to a common chamber disposed bctwe'cn the supply and cxhuustvulvc members of said two valve means.

10. Thc combination according to claim 9, said housin g means comprisingit single housing.

1 l. The combination according to claim 7, onc ofsuid valve meanscomprising a double two-wiry valve and thc second valvc mcuns comprisinga three-way valve, pressure responsive means on each vulvcfor shiftingit in one direction, and pilot valves connected to said lastmcmionedmeans.

I 2. The combination according to claim I l said valve means normallybeing in positions with their supply valve members closcd and theirexhaust valve mcmbcrs open.

13 In a safety control valve system for-fluid actuated devices a housinghaving a supply port a control port and an exhaust port, first amlsecond normally closed valve means in said housing each valve meanshaving facing suppl} and exhaust valve members supply and er haust valveseats alternately engageable by the supply and exhaust valve members ofeach valve means, a

chamber between the supply and exhaust valve seats of each valve means,a direct connection between saitl chambers whereby they constitute acontrol line chamber common to both valve means a direct connection between said control line chamber and said control port passageway meansconnecting the supply valve members of both valve means in seriesbetween said suppl} and control ports whereby one supply valve member iupstream and the other is tlmvnstream. means separating said controlline chamber from said upstream supply valve member. and a commonexhaust chamber-for both valve means leading to the exhaust port, saidCOI'HFHUH exhaust chamber being connected to the exhaust valve membersof both valve means in parallel and being sepa' rateclfrorn saidpassagim'ay means, whereby a direct exhaust passage will be providedbetween the control port and exhaust port through said control linechamber when either valve means is in its exhaust position said directexhaust passage bypassing the supply valve members of both valve means:

14. The combination according to claim 13. said supply and control portsbeing on opposite sides of said housing, said valve means being movableat right angles to the extent of the housing.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT N0. Re. 28,520

DATED i Reissued August 19, 1975 INVENTOMS) Kenneth R. Mahorney(deceased) It is certified that error appears in the abeve-dentifiedpatent and that said Letters Patent are hereby corrected as shownbelow',

Column 1, line 28, "may be" should be -may not be--.

Signed and Scaled this twenry-third D3) Of December 1975 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner nfParentsand Trademarks

1. A safety valve assembly for supplying pressurized fluid from a supplyline to a clutch and brake control line to energize the clutch andde-energize the brake and for alternatively exhausting fluid from thecontrol line to an exhaust line to de-energize the clutch and energizethe brake which comprises means defining a fluid supply line chamber andan intermediate chamber as well as a control line chamber and an exhaustline chamber, a first valve having a movable valve member cooperatingwith first and second seats, the first seat being normally Closed andthe second seat being normally open and having an actuator foractivating such valve member, a second valve having a movable valvemember cooperating with third and fourth seats, the third seat beingnormally closed and the fourth seat being normally open and having anactuator for activating such valve member, the first seat beinginterposed between the supply line chamber and the intermediate chamberand the third seat being interposed between the intermediate chamber andthe control line chamber so that such seats are effectively in serieswith one another with pressurized fluid being passed successivelythrough the first and third seats from the supply line chamber to thecontrol line chamber when the valve members are simultaneously activatedby the actuators, the second and fourth seats being both interposedbetween the control line chamber and the exhaust line chamber with suchseats being effectively in parallel with one another so that in theevent either one of the movable valve members, upon deactuation, sticksin its activated position (a) flow of pressurized fluid from the supplyline will be cut off and (b) (direct access) a direct path for exhaustedfluid will be provided from the control line to the exhaust line whichbypasses said first and third seats for insuring that the clutch andbrake are in a safe condition.
 2. The combination as claimed in claim 1in which the movable valve members are each in the form of a spoolhaving spaced, inwardly facing flanges cooperating with opposedoutwardly facing valve seats with the spools being movable endwisethrough a limited displacement for alternative closing of the valveseats.
 3. The combination as claimed in claim 2 in which the valve seatscooperating with a given spool are formed at the respective ends of acylindrical insert having lateral openings formed therein.
 4. Thecombination as claimed in claim 1 in which the housing means is unitaryenclosing all of said chambers and seats and with means for guiding themovable valve members into seated condition with respect to the seats.5. A safety valve assembly for supplying pressurized fluid from a supplyline to a clutch and brake control line to energize the clutch andde-energize the brake and for alternatively exhausing the fluid from thecontrol line to an exhaust line to de-energize the clutch and energizethe brake, which comprises a first valve in the form of a double two-wayvalve having first and second valve seats defining a total of fourports, the seats being engaged by a valve member movable between limitpositions for closing the seats alternatively, a second valve in theform of a three-way valve having third and fourth valve seats defining atotal of three ports, the seats being engaged by a valve member movablebetween limit positions for closing the seats alternatively, separateactuating means for activating the valve members, means forinterconnecting the ports associated with the first and third valveseats in series so that when the valve members are both activated,pressurized fluid is conducted in succession past the first and thirdvalve seats, means for interconnecting the ports associated with thesecond and fourth valve seats in parallel so that when the valve membersare both deactuated, exhausted fluid is conducted in parallel past thesecond and fourth valve seats and so that in the event one of the valvemembers, upon being deactuated, sticks in its activated position atleast the second or fourth seat will remain open to provide directescape of exhausted fluid from the control line.
 6. The combination asclaimed in claim 5 in which means are provided for signalling thesticking of one of the valve members.
 7. A safety control system forfluid actuated devices, comprising housing means having a supply port, acontrol port and at least one exhaust port, first and second valve meansin said housing means, each valve means having supply and exhaust Valvemembers movable simultaneously between a supply position in which thesupply valve member is open and the exhaust valve member closed, and anexhaust position in which the exhaust valve member is open and thesupply valve member is closed, means connecting the supply valve membersof said first and second valve means in series between said supply andcontrol ports, and means connecting the exhaust valve members of saidfirst and second valve means in parallel between said control andexhaust ports, whereby the movement of either valve means to its exhaustposition when the other valve means remains partially or fully in itssupply position will result in a complete cutoff of fluid pressure fromthe supply to the control port and a direct connection from the controlport to at least one of the exhaust ports, said direct connectionbypassing the supply valve members of both said first and second valvemeans.
 8. The combination according to claim 7, each valve meanscomprising a spool with inwardly facing flanges comprising the supplyand exhaust valve members.
 9. The combination according to claim 8, saidcontrol port being connected to a common chamber disposed between thesupply and exhaust valve members of said two valve means.
 10. Thecombination according to claim 9, said housing means comprising a singlehousing.
 11. The combination according to claim 7, one of said valvemeans comprising a double two-way valve and the second valve meanscomprising a three-way valve, pressure responsive means on each valvefor shifting it in one direction, and pilot valves connected to saidlast-mentioned means.
 12. The combination according to claim 11, saidvalve means normally being in positions with their supply valve membersclosed and their exhaust valve members open.
 13. In a safety controlvalve system for fluid actuated devices, a housing having a supply port,a control port and an exhaust port, first and second normally closedvalve means in said housing, each valve means having facing supply andexhaust valve members, supply and exhaust valve seats alternatelyengageable by the supply and exhaust valve members of each valve means,a chamber between the supply and exhaust valve seats of each valvemeans, a direct connection between said chambers whereby they constitutea control line chamber common to both valve means, a direct connectionbetween said control line chamber and said control port, passagewaymeans connecting the supply valve members of both valve means in seriesbetween said supply and control ports, whereby one supply valve memberis upstream and the other is downstream, means separating said controlline chamber from said upstream supply valve member, and a commonexhaust chamber for both valve means leading to the exhaust port, saidcommon exhaust chamber being connected to the exhaust valve members ofboth valve means in parallel and being separated from said passagewaymeans, whereby a direct exhaust passage will be provided between thecontrol port and exhaust port through said control line chamber wheneither valve means is in its exhaust position, said direct exhaustpassage bypassing the supply valve members of both valve means.
 14. Thecombination according to claim 13, said supply and control ports beingon opposite sides of said housing, said valve means being movable atright angles to the extent of the housing.